Merc 190 smoking

[shredder22]

I am having a problem with one of my Merc 190 engins smoking out of the valve cover return to the spark arrestor, so much that it will continually stall out the engin at idle. The engin is not smoking out the exhaust, the compression checks out and I do not have excess oil in the engin. Any ideas on the problem and solutions would be helpful, Thank you.